Floating roof sealing mechanism provided with combination weather hood and wax trough



April 25, 1961 M. w. HEISTERBERG 2,981,438

FLOATING ROOF SEALING MECHANISM PROVIDED WITH COMBINATION WEATHER HOODAND wAx TROUGH 2 Sheets-Sheet 1 Filed Feb. 19, 1959 INVENTOR Mi/fan WHeisferberg QQ R BY M ,M W

Affys.

April 25, 1961 FLOATING ROOF S EALING ME COMBINATION WEATHER Filed Feb.19, 1959 M W. HEISTERBERG CHANISM PROVIDED WITH HOOD AND WAX TROUGH 2Sheets-Sheet 2 INVENTOR. Milton W He/sferberg United States FLOATINGROOF SEALING MECHANISM PRO- 'VIDED WITH COMBINATION WEATHER HOOD AND WAXTROUGH Milton W. Heisterberg, Chicago Heights, Ill., assignor to GeneralAmerican Transportation Corporation, Chicago, 11]., a corporation of NewYork Filed Feb. 19, 1959, Ser. No. 794,454

4 Claims. (Cl. 220-26) This invention relates to storage tanks employingfloating roofs and used for the storage of liquids in the oil industryand elsewhere and more particularly designed for use with liquids havinga congealable constituent which at some times may be present in eitherliquid or congealed form due to different temperature conditions.

For example, in crude oils certain waxy products, under certaintemperature conditions, congeal on the inside of the tank wall inposition to be scraped oil by the sealing structure provided between thefloating roof and the tank wall so as to fall inwardly either onto thesealing structure or else onto the protective covering for the seal.Where no provision is made for closing the gap between the floating roofand the tank wall, the flexible sealing structure between the floatingroof and the tank wall will receive the wax and become clogged therebyso as to cause subsequent damage. When a protective seal cover isprovided and the wax is hot from the sun, this waxy product may flowonto the roof and into the drains and subsequently congeal and clogthem, or may spread and make a slippery coating on the root. In eithercase, the waxy product is lost from the lading in the tank.

One of the principal objects of the present invention is to provide astorage'tank employing a floating type roof wherein any waxy productwhich congeals and is scraped off the side wall of the tank, will betrapped and held before it reaches as portion of the roof or sealstructure where it can cause damage or danger, for example, because ofthe safety hazard of a slippery deck, or because of the fire hazard ofwidely spread combustible material.

Another object of the invention is to provide a trapping structure whichcan be incorporated readily in existing tanks and floating roofstructures, and also one which is 10f a flexible character so as toaccommodate itself to variations in dimensions of the tank wall and theseal structure associated therewith.

These and other objects and advantages of the present invention will beapparent from the following description of certain preferred embodimentsthereof, taken in connection with the accompanying drawings, wherein:

Figure l is a fragmentary plan view of a peripheral portion of thefloating tank roof constructed in accordance with the invention, thetank wall being shown in cross section, and the shoe of the seal beingalso partially shown in cross section;

Figure 2 is a fragmentary vertical cross sectional view of the roof andtank taken substantially along the line 2-2 of Figure l;

Patented Apr. 25, 1961 liquids, and particularly liquid petroleumproducts such as crude oils.

The liquid level 11 in the tank is expected to rise and fall from timeto time, and the roof of the present invention is arranged to float onthe liquid and to rise and fall with the changes in the liquid level,being commonly designated as a floating roof of the pontoon type. Theroof includes at its outer periphery a pontoon 12 having an upper wall12a which slopes downwardly and inwardly from its outer edge. Extendinginwardly from the pontoon 12, is a deck 13 which may or may not includeanother pontoon at the center of the tank in accordance with theparticular type of roof being constructed.

The annular outer pontoon 12 is spaced from the wall 10 of the tank, anda seal is preferably provided in this space and this seal mechanism maycomprise an outer sliding cylindrical metal shoe 16 of a flexible natureto conform to irregularities in the tank wall 10, and an annularflexible gas impervious curtain or fabric seal 17 which is clamped tothe outer wall of the pontoon 12 by a seal bar 18, and by a plurality ofnut and bolt connections 19 to provide a gas tight joint. The outerperiphery of the fabric seal 17 is clamped by a seal bar 21 and aplurality of nut and bolt connections 22 to also provide a gas tightjoint.

At a plurality of points about the periphery of the floating roofstructure, pressure and supporting rods 26 are provided, each having achannel piece 27 at the outer end thereof secured to the shoe 16. Eachrod 26 is slidably engaged within a pipe or a cylinder 28 supported onthe outer wall of the pontoon 12 and having a compression spring 29housed therein. This structure provides a yieldable pusher mechanismwhich serves to support the shoe 16 and also to urge it against the tankwall 10.

An annular cover structure or weather hood is provided between thesliding shoe 16 and the pontoon 12 to protect the parts of the seal andto cover the open space between the pontoon 12 and the shoe 16 so as todrain onto the pontoon 12 and the deck l3 rain and other moisture thatwould otherwise fall into this space. For this purpose an annular seriesof brackets 31 are secured to the inner surface of the shoe 16 adjacentits upper inturned edge 16a and each bracket 31 includes an upstandingflange 31a secured flush against the shoe 16, and is provided adjacentits lower edge with a pair of inwardly and downwardly directed flanges31b, which are spaced apart to receive the outer edges of an annularseries of overlapped cover plates 32, which are loosely secured in placeby headed pins 33, extending through suitable apertures in the flanges31b and the plates 32. The inner edges of these plates 32 are supportedin spaced relation from the pontoon 12 by suitable supports 34. Byproviding a sectional annular cover plate structure, with the sectionsor plates in overlapping relation, a weather-tight closure is providedwhich also accommodates itself to changes in contour of the shoe as itfollows any irregularities in the tank wall.

Means are provided for collecting any congealed productssuch as waxeswhich are deposited on the inner surface of the tank wall 10 and scrapedloose therefrom by movement of the shoe 16, and this means preferablycomprises an annular shallow trough structure of flexible character,which will retain the waxes while permitting overflow of any rain wateror the like. This annular trough structure is comprised of overlappedbent plates 36 which have their outer edges disposed between therespective flanges 31b of the brackets 31, and have suitable aperturesto receive the pins 33 so as to be secured in place easily by existingstructure. These plates 36 provide a trough 37 formed by an upturnedinner edge 36a of each plate 36.

of conventional construction. .lapped one upon the other as seen inFigure 4, and the r assuage .Erom the above description it will be seenthat the trough 37 provides for satisfactory retention of waxy products,even when melted, as their more or less viscous nature would precludeany appreciable loss through the cracks or spaces provided between theoverlapped plates 36'. At the same time this tro'ugh structure isnotwater tight because water will seep more or less easily through thesecracks or crevices, or if received in volume will flow over theup-turned edges 36a.

Referring to Figure 4 there is illustrated a modified form of sealstructure for a floating roof of the type described herein together witha modified form of annular weather hood and trap structure forthe waxyproducts. in this form of the invention, the flexible fabric seal 117 issupported between the upper surface of thepontoon 112 and the upperportion of the sliding shoe 1,16. The inner edge 117a of the flexiblefabric seal 1.17 is disposed horizontally on top of a channel-shapedmounting member 141 secured about the upper surface 112a of the pontoon112, being secured in place by an annular seal bar 142 suitably securedto the upper flange of the channel-shaped member 141. The outerperipheral edge of the fabric seal 117 is disposed between the shoe 116and an annular seal bar 143 clamped in place by a retaining channel 144secured to the shoe 116 by a plurality of bolt and nut structures 145.The retaining or clamping channel 144 also provides means for securingin place an annular series of adapter strips 146 which have their outerdown turned flanges 146a in engagement with the top 143a of the seal bar143, and secured by one web of the channel 144 against the upper edge ofthe fabric seal 117. Each strip 146 extends upwardly from its outerflange 146a and then curves inwardly and downwardly therefrom to pro-,vide an inwardly and downwardly projecting inner flange 146b whichprovides a mounting means for the weather hood and trap structure plates147 which extend inwardly and downwardly therefrom to rest on the sealbar 142.

The inner flanges 14Gb and the plates 147 are suitably apertured toreceive loosely a series'of securing bolt and nut constructions 148having spring washer retainer 149 The adapters 146 are overweather hoodand trap plates 147 are similarly overlapped, having their inner edgesupturned at 147b, to form a trough or trap 137, which overlies theupwardinwardly sloping top 112a of the pontoon 112.

This structure serves not only to convey any, precipitation receivedonto the pontoon 112 and thence to the roof structure to be accommodatedby conventional drainage means of the tank, but also provides a trapforthe waxy products scraped loose from the tank wall 110 by the shoev116 and to retain these waxy products for subsequent removal and returnto the lading of the tank.

Figure 5 shows in fragmentary fashion a trap structure .which comprisesan inclined plate 251 which may be similar to either ,of the types shownin Figures 2 or 4,

:and which has secured thereon a plurality of angle-shaped .trap members252 to form a series of trap 237 for the waxy products, these plates 251being overlapped and mounted in the general fashion shown in either ofFigures 2 or 4. In this embodiment, the composite trap structurecomprises the two concentric low annular riflles provided by the members252 for the purpose of selectively trapping -fioating roof, but whichwill permit passage of precipitated rain or other moisture onto the tankroof for disposal.

.In this way the seal structure is protected, and the safety .hazard ofa tank roof made slippery by wax is eliminated,

as well as the fire hazard of a widely spread combustible material.Also, a large percentage of the waxy product which may be removed fromthe tank wall is available for return to the lading of the tank, therebyretaining closely its original constituents for subsequent processing.

The foregoing description of certain embodiments of the presentinvention has been made for clearness of understanding only and nounnecessary limitations are in tended thereby, for it will be apparentto those skilled in the art that various modifications may be made inthe present tank structure within the'sphere and scope of the appendedclaims.

What is claimed is:

l. In combination with an upstanding substantially cylindrical tank forstorage of liquid petroleum products, a substantially annular floatingroof for said tank that rests on the stored petroleum products and thatrises and falls as the amount of the stored petroleum product varies,and a substantially annular peripheral seal carried by said roof andextending radially outward therefrom to theside wall of said tank andincluding a substantially annular shoe pressed radially outwardlyagainst said side wall and having sufiicient flexibility to conform tothe configuration of said side wall, whereby said shoe scrapes waxyconstituents off of said side wall; and a weather hood carried by saidshoe and including a plurality of downwardly and inwardly inclinedshingle-like plates arranged in an annular array over said seal with theside edges thereof in overlapping relation between said shoe and roofthus constituting a water shed onto said roof, and said hood including aplurality of upwardly directed projections arranged in annular arraywith the side edges thereof in overlapping relation between said shoeand roof and defining a substantially annular trap wall against whichwaxy constituents scraped from said'tank wall may accumulate and overwhich water may flow and shed onto said roof.

2. The storage tank combination set forth in claim 1, in which anannular series of mountings are on said flexible shoe, and saidoverlapping plates and projections are so interrelated and carried bysaid mountings as to accommodate changes in contour of said flexibleshoe as it follows the tank wall.

3. In combination with an upstanding substantially cylindrical tank forstorage of liquid petroleum products, a substantially annularfloatingroof for said tank that rests on' the stored petroleum products and thatrises and falls as the amount 'of the stored petroleum product varies,and a substantially annular peripheral seal carried by said roof andextending radially-outward therefrom to the side wall of said tank andincluding a substantially annular shoepressed radially outwardly againstsaid side wall and having sufficient flexibility to conform to theconfiguration of said side wall, whereby said shoe scrapes waxyconstituents off of said side wall; and a weather hood carried by saidshoe and including a plurality of downwardly and inwardly inclinedshingle-like plates arranged in an annular array over said seal with theside edges thereof in overlapping relation between said shoe and roofthus constituting a water shed onto said roof, said annular array ofplates being in upper and lower superimposed annular series in which theside edges 'of the adjacent plates forming the individual series are inoverlap with each other, said plates in said upper series includingupwardly directed projections arranged in annular array and having sideedges in overlapping relation rests: on the stored petroleum productsand that rises and 5 falls as the amount of the stored petroleum productvaries, and a substantially annular peripheral seal carried by said roofand extending radially outward therefrom to the side wall of said tankand including a substantially annular shoe pressed radially outwardlyagainst said side wall and having suflicient flexibility to conform tothe configuration of said side wall, whereby said shoe scrapes waxyconstituents oil of said side wall; and a weather hood including aplurality of downwardly and inwardly inclined shingle-like platescarried by said shoe and arranged in an annular array over said sealwith the side edges thereof in overlapping relation between said shoeand roof thus constituting a water shed onto said roof,

References Cited in the file of this patent UNITED STATES PATENTS1,931,551 Larson Oct. 24, 1933 2,754,026 Wiggins July 10, 1956 2,802,591Wiggins Aug. 13, 1957 2,855,122 Ulm et al. Oct. 7, 1958

